1. Field of the Invention
The present invention relates to a disk drive flexure used in a hard disk drive (HDD) for an information processing apparatus, such as a personal computer.
2. Description of the Related Art
A hard disk drive is used in an information processing apparatus, such as a personal computer. The hard disk drive comprises a magnetic disk that rotates around a spindle, a carriage that turns around a pivot, etc. A disk drive suspension is disposed on an arm of the carriage.
The disk drive suspension comprises a load beam, a flexure lapped on the load beam, etc. A slider is mounted on a gimbal portion formed near the distal end of the flexure. The slider is provided with elements (transducers) for access, such as reading or writing. The suspension, flexure, etc., constitute a head gimbal assembly.
The flexure may be of any of various practical types corresponding to required specifications, and a flexure with conductors is disclosed as one example thereof in Jpn. Pat. Appln. KOKAI Publication No. 2004-133988 (Patent Document 1). The flexure with conductors comprises a metal base, insulating layer formed on the metal base, and conductors formed on the insulating layer. The metal base consists of a thin stainless-steel plate. The insulating layer consists of an electrically insulating material, such as polyimide. The conductors consist of copper. Respective one ends of the conductors are connected to elements (e.g., magnetoresistive [MR] elements) of the slider. The other ends of the conductors are connected to an electronic circuit, such as an amplifier.
The impedance of a conductive circuit portion of the flexure is expected to be reduced in order to match the amplifier and slider elements and reduce energy consumption. In laying out the flexure in a narrow space within the disk drive, the thickness and width of the conductive circuit portion should be minimized.
The flexure disclosed in Patent Document 1 comprises a conductive circuit portion of a multi-layer type. FIG. 17 shows an example of the multi-layer conductive circuit portion. In the conductive circuit portion shown in FIG. 17, an insulating layer 2 is formed thicknesswise relative to a metal base 1. A first conductor 3 is formed on the insulating layer 2. The first conductor 3 is covered by a first cover layer 4 made of an insulating material. A second conductor 5 is formed on the first cover layer 4. The second conductor 5 is covered by a second cover layer 6 made of an insulating material.
In the multi-layer conductive circuit portion shown in FIG. 17, the conductors 3 and 5 are located thicknesswise, so that their width W1 can be made relatively large despite the narrowness of the conductive circuit portion. Thus, the conductive circuit portion has an advantage that its impedance can be reduced. Since the metal base 1, insulating layer 2, conductors 3 and 5, and cover layers 4 and 6 are lapped thicknesswise relative to the conductive circuit portion, however, a thickness H1 of the circuit portion is inevitably large.
FIG. 18 shows a conventional flat-type conductive circuit portion. In this flat circuit portion, first and second conductors 3 and 5 are arranged transversely relative thereto in parallel relation along an insulating layer 2 formed on a metal base 1. The conductors 3 and 5 are covered by a cover layer 4. The flat conductive circuit portion has an advantage over the multi-layer version in having a smaller thickness H2. Since the pair of conductors 3 and 5 are arranged transversely within the width W2 of the conductive circuit portion, however, the conductors 3 and 5 cannot be widened. Thus, there is a problem that the inductance and impedance of the conductive circuit portion are high.